1. Field of the Invention
This invention relates to a method and means for detecting an abnormally low tire pressure in a vehicle having dual wheel assemblies and alerting the driver of said condition.
2. Description of the Prior Art
The damaging effects of operating a dual wheeled road transport vehicle having an underinflated tire are well known. Driving with one of the tires flat for a relatively short distance will ruin the tire and possibly result in damage or failure of the properly inflated tire due to overheating or rubbing of the sidewalls. Unlike single wheeled vehicles, the underinflation of one of a pair of dual tires often passes unnoticed by the driver until the damage has occurred.
The high expense of tire losses and the potential hazards to the travelling public have caused many inventors to focus their attention on the problem. Numerous solutions in the prior art have revolved about direct monitoring of the pressure on each tire coupled with alarm systems. One such approach using miniature transmitters coupled to pressure detectors on each tire is disclosed in the U.S. Pat. No. 3,950,726 to Fujikawa et al, granted Apr. 13, 1976. Another approach using movable magnets, responsive to pneumatic pressure, for triggering an alarm is disclosed in the U.S. Pat. No. 3,978,448 to Vago, granted Aug. 31, 1976.
Such devices necessarily rely upon direct contact with the rotating tire or wheel. This reliance produces numerable difficulties in the ultimate signal conveyance or transmission.
Other devices, such as infrared detectors, mounted above the tires rely upon the heat generated by the underinflated tire. As heat is the primary enemy of the tire, this type of device often works too slow to prevent irreparable harm. Furthermore, the presence of mud or dirt on the sensing unit greatly interferes with the apparatus efficiency.
It is therefore an object of this invention to devise a method and means for detecting an abnormally low pressure in one tire of a dual wheel assembly, which does not rely upon direct contact with the tire. It is a further object of this invention to provide an effective system for alerting the driver prior to damage of the tire.